This invention relates to a process for manufacturing a thermoplastic polyurethane product and more particularly to a process for manufacturing such a product suitable for use in automotive wheel suspensions systems.
Typically, conventional wheel suspension systems for automotive vehicles have consisted of a number of components linked together and provided with various elastomeric components such as bushings, bumpers, spacers, washers, mounts and the like which function to transmit motion, absorb shock loads and allow limited displacement between connected components. Initially, such elastomeric components were formed of rubber. It was found, however, that the use of rubber in such applications was unsatisfactory in that over a period of use, rubber will dryrot and tear under stress, resulting in failure and requiring replacement.
More recently, the material failure problem of rubber has been solved by the use of thermoplastic polyurethane materials which have not only a deflection rate curve comparable to rubber but also a high abrasion resistance, high tear strength and excellent shock absorption, coupled with hardness, a wide range of flexibility and elasticity, solvent resistance, especially to hydrocarbons, and excellent resistance to oxygen aging. Components formed of polyurethane materials are not only more durable than compounds made of rubber but weigh less and can be formed smaller to conserve space and energy in vehicles.
In the use of polyurethane materials in some wheel suspension components, however, it has been found that under dynamic loading, such materials have a tendency to squeak. It therefore has been desirable to provide a polyurethane material suitable for use as a wheel suspension system component which will not produce a squeaking sound under dynamic load conditions.
Accordingly, it is the principal object of the present invention to provide a novel process for manufacturing an improved product formed of a polyurethane material.
Another object of the present invention is to provide a novel process for manufacturing an improved product formed of a polyurethane material such as a bushing, bumper, spacer, washer, mount and the like.
A further object of the present invention is to provide a novel process for manufacturing various components such as bushings, bumpers, spacers, washers, mounts and the like suitable for use in wheel suspension systems of vehicles.
A still further object of the present invention is to provide a novel process for manufacturing an improved article formed of a polyurethane material which will not produce a squeaking noise under dynamic load conditions.
Another object of the present invention is to provide a novel process for manufacturing an improved component of a wheel suspension system, formed of a polyurethane material, which will not produce a squeaking noise during normal usage of such system.
A further object of the present invention is to provide a novel process for manufacturing a product formed of a polyurethane material having a high lubricity which is simple in procedure, economical in practice and highly effective in performance.
A still further object of the present invention is to provide an improved product formed of a polyurethane material.
Another object of the present invention is to provide a novel component for a wheel suspension system such as a bushing, bumper, spacer, washer, mount and the like, formed of a polyurethane material.
A further object of the present invention is to provide a novel article of manufacture formed of a polyurethane material which is functional under dynamic load conditions without producing squeaking noises.
Other objects and advantages of the present invention will become more apparent to those persons having ordinary skill in the art to which the present invention pertains from the following description taken in conjunction with the accompanying drawings in which: